Recent reports have indicated that Linux continues to gain a larger share of the server market, while Microsoft Windows and variations of Unix continue to lose significant market shares. Linux has become the dominant server OS type of choice, and for web servers in particular, Linux is almost the default.
Nevertheless, to call Linux a single operating system would be a mistake. Linux is the kernel present in any number of operating systems, from Ubuntu to Android. The variations of the GNU/Linux OS are often called “distributions”, and they perhaps number in the hundreds.
In the past, we have highlighted some of those distributions. But which one is the best for servers? CentOS has become very popular, and it is the OS that cPanel users typically prefer, but they might also use Red Hat Enterprise Linux or even FreeBSD. For package management, some system administrators swear by Debian, believing its APT package management system to be the best thing since sliced bread. Still others love Gentoo for its superior optimization capabilities and easy of customization.
The truth is, much of this depends on preference. All of the major server-based Linux distributions are configured to meet a variety of needs and security concerns. You should study the features, documentation, and performance ratings of each distribution before making your decision. Moreover, make sure all of your hardware is supported, and make sure the OS you choose has all of the applications you want in its repository, or at least supports the apps you want to install.